In the industrial synthesis of alkaline earth metal alkylates, for example from alkaline earth metal filings and an alkanol, the corresponding alkylate is obtained with an irregular grain structure. However, many applications demand specially fabricated products; for example, spherical particles of relatively monomodal particle size distribution. Active catalyst support substances based on magnesium ethylate having a spherical particle habit and an average particle diameter of 10-20 .mu.m having proved particularly suitable for the polyolefin synthesis using Ziegler catalysts (see Published European Applications 0 236 082 and 0 159 150). The processes for the preparation of spherical or spheroid alkaline earth metal alkylates prove to be expensive industrially; it is true that spray-drying of carbonized ethanolic magnesium ethylate solutions with subsequent decarbonization by heat treatment in a stream of nitrogen (Published European Application 0 236 082) yields a magnesium ethylate powder having an approximately spherical particle form, but this powder has a highly structured surface, resulting from the collapse of hollow spheres formed during the spray process (raisin structure). Since the spray-drying must be carried out under inert gas conditions, the process is very expensive industrially if the solvent is to be recycled from the large stream of inert gas required for the spray-drying. Particle sizes of &lt;10 .mu.m are not accessible in industrial spray installations using this process nor by precipitation reactions in accordance with Published European Application 0 214 891 in complex solvent mixtures.